Life in the Ocean’s Three-Dimension World
THE ocean is a veritable reservoir of life. Not only does its surface occupy more than. 70 percent of the earth’s area, but its tremendous depth, averaging well over two miles, makes it a three-dimensional world of enormous capacity having many levels throughout its entire domain.
Life is found in any part of the ocean, at every depth. Along its shores it teems with intensely active life. At a lower level, on the continental shelf, life is also very active. Farther out, in the open seas, most life exists in the higher levels near the surface. But even in the abyssal depths of the deepest trenches life is there, performing its part in the ocean’s ecological system.
The Food Chain
Obviously the countless billions of sea animals require a prodigious amount of food. Though there are great quantities of seaweed, such as in the Sargasso Sea, it is by no means the primary food source. In fact, seaweed plays a very small part. Actually, more than 90 percent of the basic organic material that builds and fuels all life in the sea is synthesized within the lighted layers of open water by the many varieties of “phytoplankton.”
Phytoplankton are microscopic plants that float near the surface where they can utilize the sunlight. They must have light to do their work and to live, just as most earthly plants need sunlight. Phytoplankton manufacture food by photosynthesis, a process utilizing energy from sunlight to convert mineral nutrients in the ocean into food. This is vital for animals, since they cannot synthesize their own food.
So, just as vegetation on land provides the basic food for all land animals, plant life forms the food foundation for the ocean dwellers.—Gen. 1:29, 30.
Great layers of phytoplankton drift in the ocean, usually being most dense where “upwellings” bring mineral nutrients up from the ocean floor, or where currents carry such food. The primary eaters of the phytoplankton are small animals called “zooplankton.” These sink below the surface to a depth of from 1,000 to 4,000 feet during the daytime and rise again nightly to engage in a frenzy of feeding. Other small fish that eat phytoplankton and some that feed on the zooplankton accompany this migrating host, all together forming what is known as the “deep scattering layer.” So thick is it that during the early use of sonar depth finders this layer was often mistaken for ocean bottom, resulting in inaccuracies in maps of the ocean floor. During wartime submarines took shelter below the “deep scattering layer,” safe from detection by the sonar of destroyers.
Eating the zooplankton are the “nekton” (meaning “swimming”). These predators include thousands of varieties of fishes. In the food “pyramid” roughly 1,000 pounds of ocean plants (at the bottom of the pyramid) will support 100 pounds of plant-eating animals (the next step in the pyramid). This, in turn, will produce ten pounds of meat-eating marine animals. Finally, ten pounds of fish will build one pound of human flesh. To supply the market with ten pounds of fish therefore requires the ocean to supply 1,000 pounds of microscopic plankton “fodder.”
Some idea of the monumental task the ocean performs in producing food is grasped when we consider that the fur seals using the Pribilof Islands in the Bering Sea as a breeding ground—these seals alone—consume some three and a half billion tons of fish a year. What a bountiful food source is the ocean, a handiwork of the Creator! As the psalmist wrote:
“How many your works are, O Jehovah!
All of them in wisdom you have made.
The earth is full of your productions.
As for this sea so great and wide,
There there are moving things without number,
Living creatures, small as well as great. . . .
All of them—for you they keep waiting
To give them their food in its season.
What you give them they pick up.
You open your hand—they get satisfied with good things.”
The “Red Tide”
Occasionally a certain type of microscopic sea life known as “dinoflagellates” undergoes a “population boom,” concentrating in astronomical numbers. They multiply to such a high density that large areas of water are turned red, brown or amber by their pigments—a phenomenon known as a “red tide.” The concentration may become too great for their own survival, and they produce in the water a very toxic substance that kills fish and seabirds in the area. The poisons released from the water into the atmosphere by breaking waves are irritating to the human respiratory system, sometimes causing the temporary closing of coastal resorts. A high yield of hydrogen sulfide may result that can blacken houses painted with white lead in a nearby coastal city.
Marine Methods of Protection for Survival
One may wonder how any particular form of sea life can avoid extinction in the face of all its predators. But the various kinds of marine life have many different ways of survival as a species. One way is by superprolific reproduction. The tiny diatom, most numerous of microscopic plants, may have a billion descendants in one month. The haddock lays up to nine million eggs at a time. The oyster lays up to 500 million eggs a year. One billion mackerel off the south shore of Cape Cod produce an estimated sixty-four trillion eggs during the mating season. The eggs and the young of fish and other sea animals are quickly gobbled up by a whole host of predators of every description. In the case of the mackerel, it was estimated that out of every million eggs only one to ten fish survive to maturity. The mortality rate is between 99.98 percent and 99.99 percent. Yet there are plenty of mackerel, haddock and oysters. The same is true of many other animals, such as clams, shrimps, and so forth. It is only the predator man that tends to unbalance matters and that threatens to destroy entire species.
Other fish, instead of relying altogether on numbers, protect their eggs or young. In the case of some sharks, the eggs are hatched and the newborn fish live for a time in the mother’s hinder parts. Some fish fasten their eggs down to rocks, plants, and so forth; some shield them with foams and membranes. In other species the male carries the eggs in his mouth or in a pouch (as does the sea horse) until they hatch. Often, however, the young are on their own after they hatch. But the dolphin, a mammal, continues to guard its young from enemies.
Since practically all sea animals have predators on the hunt for them, camouflage is frequently employed. The butterfly fish, for example, has an eye spot on its body to direct the attacker away from the head. The backs of open-sea fishes are green or black because the sea, seen from above, has that appearance. But looking from below, the ocean surface appears silvery or whitish. Correspondingly, the underside of most fish is of this color.
The sea cucumber has perhaps the strangest method of protection. When in danger, he simply expels his intestines. Evidently the hungry predator prefers to make a meal out of the intestines rather than the leathery, tasteless bag that is left. Then the “empty bag” grows new intestines. Stinging cells help the more static or stationary animals, such as the man-of-war, to hold off their enemies. Others rely on speed, alertness, size or strength. Some of the deep-sea squids possess a unique protective device. They discharge a luminous cloud to cover their escape. Other fish emit strong flashes of light to throw predators off target or temporarily “blind” them.
In the ocean’s three-dimension world, where vision is limited to a distance of about a hundred feet, and where the surrounding medium is much heavier than air, the Creator has provided equipment that land animals do not have. One of these is a “sixth sense,” possessed by most of the fast-swimming fishes. This consists of a longitudinal system of canals that run from head to tail, called the “lateral line.” It enables the fish to sense even very slight changes in outside pressures. In this way thousands of fish in a “school” can stay together and move in perfect unison, quickly changing direction as one body. Also, from quite a distance they are warned of approaching enemies. By this sense they can also avoid bumping into obstacles, such as the glass wall of an aquarium.
One of the most amazing features of the ocean’s ecological system is the interdependence of life there, and the balance of life that is maintained. While those that are hunted by predators have protective equipment, the hunters are themselves provided with the most sophisticated means of locating and catching their prey. And while enough fish are captured by the hungry predators to supply them with food, enough individuals survive to keep each species in existence. If there were no predators that liked to eat oyster eggs or young turtles, the ocean would soon be overrun by oysters or turtles. But if oysters and turtles were completely wiped out by their predators, the predators would go out of existence also. Only an all-wise Creator could have provided the conditions and designed the hunting and protective equipment to achieve such a delicate balance as this.
As to hunting equipment, starting near the bottom of the food “pyramid,” we find, according to the description of one oceanographer writing in Scientific American (September 1969), “eyes in microscopic herbivorous animals, filters of exquisite design, mechanisms and behavior for discovering local concentrations, complex search gear and, on the bottom, attachments to elicit the aid of moving water in carrying out the task of filtration.” Certain sea snails use large, often sticky, transparent nets, some as large as six feet in diameter. By this means they catch the most minute microorganisms for food. One-celled amoebas locate food by chemical means.
Quite a few near-surface organisms are luminescent. But in the deeper ocean levels where sunlight hardly penetrates, if at all, at least two thirds of the sea animals produce light. Says the above-mentioned researcher: “Some fishes, squids and euphausiids possess searchlights with reflector, lens and iris almost as complex as the eye.” Others, he says, may have luminosity that mimics a small group of luminous plankton, while some do “fishing” with a light that dangles in front of them. The unwary fish that approaches the “bait” is quickly swallowed up.
The octopus uses eyes similar to man’s to locate his food. Dolphins and certain whales possess long-range hunting sonar. They emit sounds and their highly sensitive hearing detects the echo. It is thought that the sperm whale may be able to locate prey over long distances, perhaps miles. Sharks have a keen sense of smell, blood from a wounded fish attracting them from a distance.
Life in the Abyssal Depths of the Ocean Bed
On the ocean floor, two miles or more below sea level, in near-freezing temperature, pressures are tremendous and black darkness pervades. Yet even there life persists. But it seems to be more leisurely, and the population is much more scarce. Sea cucumbers up to a foot and a half in length march slowly over the muddy bottom, “eating” the mud, that is, taking in the oozy mud to get from it the tiny organisms there, or to search out the “detritus,” waste organic matter that has drifted down from above. Few of the creatures there are as large as a mouse; most are smaller than honeybees. Nets with a mesh finer than one hundredth of an inch bring up tiny clams, worms and crustaceans.
Some of the fish and other animals in the abyssal blackness are blind. Walking in a stately manner are creatures with spindly, stalklike legs with fuzzy feet, to keep them above the mud. “Brittle stars,” relatives of the starfish, sometime litter the ocean floor. Even in depths of 3,600 feet or more, an occasional ray fish swims by, looking for food on the bottom. The sea floor is covered with tracks and trails. Photographs taken 35,800 feet down in Challenger Deep southwest of Guam show a few odd animals an inch or two long. Some have the appearance of small shrimps. In the tremendous pressures at such depths man is still unable to answer affirmatively to the question that God asked Job: “In search of the watery deep have you walked about?”—Job 38:16.
The Future for Ocean Life
Now, oceanographers are highly concerned at the danger to sea life due to the greed of commercial fleets that possess advanced scientific instruments to hunt, catch and kill on a massive scale. But even more feared is pollution, also primarily the result of greed and lack of care, which has spread to an unbelievable extent, making formerly prolific fishing waters practically devoid of fish.
Such things are saddening. But the believer in God’s Word has full confidence in His ability to replenish the sea with teeming life just as he originally purposed when he commanded the sea’s inhabitants: “Be fruitful and become many and fill the waters in the sea basins.” (Gen. 1:22) Since there is such interdependency between life in the sea (both plant and animal life) and that on land, we can be sure that God will have both sea and land populated with the creatures essential to man’s everlasting welfare and happiness. This he will accomplish during the thousand-year reign of his Son, when man will be at peace with animal life, both on land and in the sea, exercising proper, loving dominion over them.—Gen. 1:27, 28; Ps. 8:4-8.
[Picture on page 17]
Meat-eating marine life